1. Falling in love.
2. Laughing till your stomach hurts.
3. Enjoying a ride down the country side.
4. Listening to your favorite song on the radio.
5. Going to sleep listening to the rain pouring outside.
6. Passing your final exams with good grades.
7. Time spend with your family.
8. Being part of an interesting conversation.
9. Helping anyone.
10. Laughing at yourself.
11. Sharing a wonderful dinner with all your friends.
12. Laughing without a reason.
13. "Accidentally" hearing someone say something good about you.
14. Watching the sunset.
15. Listening to a song that reminds you of an important person in your life.
16. Having a great time with your friends.
17. Seeing the one you love happy.
18. Wearing the shirt of a person you love and smelling his/her perfume.
19. Visiting an old friend of yours and remembering great memories.
Well there are many others that can be added to the list. I listed here whatever i got in mind and its your turn to add further :)
Prayers n Best wishes for all.